Method and apparatus for sensing the rotor position of a switched reluctance motor without a shaft position sensor
AssigneeThe Texas A&M University System
InventorMehrdad Ehsani
Life of this patent
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Abstract
Apparatus and method for detecting rotor (12) position in a switched reluctance motor (18) having multiple stator phases (A--A', B--B', and C--C'). A multiplexer (48) intermittently connects a known resistor (54) to a non-conducting stator phase. Circuitry (62 and 68) detects the amplitude of the current passing through the resistor (54) and the phase difference between the varying voltage and the current passing through resistor (54). The resulting signal is proportional to the position of rotor (12).
Claims28
A method of detecting rotor position in a switched reluctance motor having multiple stator phases which are energized in synchronism with rotor position by a commutating signal comprising:
- applying a sinusoidal signal to a non-excited stator phase of the motor, the frequency of said sinusoidal signal being different than the frequency of the commutating signal;
- detecting variances in a predetermined characteristic of said sinusoidal signal and;
- generating an indication of the position of said rotor in dependence upon said detected predetermined characteristic of said sinusoidal signal.
A method of detecting rotor position in a switched reluctance motor having multiple stator phases energized in synchronism with the position of the rotor, comprising:
- connecting a known resistance in series with a nonconducting stator phase;
- applying a periodically varying voltage to said known resistance and said nonconducting stator phase;
- and
- detecting the phase difference between the varying voltage and the current passing through said resistance, wherein said phase difference is a function of the inductance of said nonconducting stator phase and a function of the position of said rotor.
Apparatus for detecting rotor position in a switched reluctance motor having multiple stator phases which are energized in synchronism with rotor position by a commutating signal comprising:
- circuitry for applying a sinusoidal signal to a non-excited stator phase, the frequency of said sinusoidal signal being different than the frequency of the commutating signal driving the motor;
- circuitry for detecting a characteristic of said sinusoidal signal;
- and
- circuitry for generating an indication of the position of said rotor in dependence upon said detected characteristic of said sinusoidal signal.
Apparatus for detecting rotor position in a switched reluctance motor having multiple stator phases energized in synchronism with the position of the rotor, comprising:
- circuitry for connecting a known resistance in series with a nonconducting stator phase;
- a source for applying a periodically varying voltage to said known resistor and said nonconducting stator phase;
- and
- circuitry for detecting the phase difference between the varying voltage and the current passing through said resistance, wherein said phase difference is a function of the inductance of said nonconducting stator phase and a function of the position of said rotor.
Apparatus for detecting rotor position in a switched reluctance motor having multiple stator phases energized in synchronism with the position of the rotor, comprising:
- a multiplexer connected to the stator phases, said multiplexer intermittently connecting a known resistor in series with a nonconducting stator phase;
- a source of periodically varying voltage coupled to said known resistor for being applied to said nonconducting stator phase;
- a first threshold crossing detector coupled to said resistor for detecting the phase difference between the varying voltage and the current passing through said resistor;
- and
- a second threshold crossing detector coupled to said resistor for detecting the amplitude of the current passing through said resistor, wherein said detected amplitude and phase difference is a function of the inductance of said nonconducting stator phase and a function of the position of said rotor.
Apparatus for detecting rotor position in a switched reluctance motor having multiple stator phases energized in synchronism with the position of the rotor, comprising:
- a multiplexer connected to the stator phases, the multiplexer connecting a known resistance in series with a non-excited stator phase;
- a periodically varying voltage source coupled to the known resistance and the non-excited stator phase;
- a first threshold crossing detector coupled to the voltage source for detecting the phase of the voltage source;
- a second threshold crossing detector coupled to the terminals of the known resistance for detecting the phase of the current flowing through the known resistance;
- and
- a comparator for receiving the outputs of the first and second threshold crossing detectors and for generating a signal related to the phase difference between the voltage source and the current flowing through the known resistance, wherein the phase difference is a function of the inductance of the non-excited stator phase and a function of the position of the rotor.
A method of detecting rotor position in a switched reluctance motor having multiple stator phases which are energized in synchronism with rotor position by a commutating signal comprising:
- applying a periodically varying signal to a non-excited stator phase of the motor, the frequency of said varying signal being different than the frequency of the commutating signal;
- detecting the phase difference between the voltage and current of said non-excited stator and a resistance connected with said non-excited stator;
- and
- generating an indication of the position of said rotor in dependence upon said phase difference.
A method of detecting rotor position in a switched reluctance motor having multiple stator phases which are energized in synchronism with rotor position by a commutating signal comprising:
- applying a periodically varying signal to a non-excited stator phase of the motor, the frequency of said varying signal being different than the frequency of the commutating signal;
- detecting variances in the amplitude of the current drawn by said non-excited stator and the phase difference between the voltage and current of said non-excited stator;
- and
- generating an indication of the position of said rotor in dependence upon said amplitude and phase difference.
Apparatus for detecting rotor position in a switched reluctance motor having multiple stator phases which are energized in synchronism with rotor position by a commutating signal comprising:
- circuitry for applying a periodically varying signal to a non-excited stator phase, the frequency of said varying signal being different than the frequency of the commutating signal driving the motor;
- a resistance coupled to said non-excited stator phase;
- circuitry for detecting the phase difference between the voltage and current of said non-excited stator phase and said resistance;
- and
- circuitry for generating an indication of the position of said rotor in dependence upon said detected phase difference.
Apparatus for detecting rotor position in a switched reluctance motor having multiple stator phases which are energized in synchronism with rotor position by a commutating signal comprising:
- circuitry for applying a periodically varying signal to a non-excited stator phase, the frequency of said varying signal being different than the frequency of the commutating signal driving the motor;
- a resistance coupled to said non-excited stator phase;
- circuitry for detecting the amplitude of the current drawn by said non-excited stator phase and the phase difference between the voltage and current of said non-excited stator phase;
- and
- circuitry for generating an indication of the position of said rotor in dependence upon said detected amplitude and phase difference.
Dependencies are inferred from the claim text.